ABSTRACT
The relationship between steroid hormones and brain function has generally been considered to date from the point of view of feedback regulation of brain and anterior pituitary activity by the secretory products of endocrine glands. Steroids can also elicit very rapid changes in neuronal excitability, which are likely to be mediated by plasma-membrane bound receptors rather than by genomic mechanisms. Women characteristically attribute feelings of “well-being” and being “energetic” and “active” and the like to the late follicular phase of the menstrual cycle; this is a period of characteristic locomotor hyperactivity in rodents. Adenosine, a naturally occurring compound in the brain, is a potent depressant of the firing of central neurons. It inhibits activity primarily by depressing the release of neurotransmitters from presynaptic nerve terminals and by a direct hyperpolarizing action on central neurons. Premenstrual tension and postpartum depression share characteristic symptoms such as irritability, increased tension, and exhaustion; their occurrence coincides with a fall in circulating progesterone levels.
